Zircon U-Pb Age of Xiaomiao Formation of Proterozoic in the Eastern Section of the East Kunlun Orogenic Belt

Abstract

After detailed means of field geological survey,petrologic study and LA-ICP-MS zircon U-Pb chronology method about Xiaomiao Formation,the age of the metamorphic basement formed in Pre-Cambrian in Kekesha area of Xiangride Town in the eastern section of the East Kunlun orogenic belt is discussed.The results show that Xiaomiao Formation is mainly a suite of quartz-consisted metamorphic rocks,which can be categorized into 4 classes,such as rock assemblages of biotite quartz schist-quartzite,gneiss-schist,hornblende schist-biotite quartz schist and quartzite-marble.These characteristics reveal that the original rock assemblage of the rocks may be a suite of volcano-sedimentary formation,which belongs to sedimentary system from shallow sea to continental margin in environment and low-amphibolite facies of middle pressure in metamorphic condition.Furthermore,the zircon U-Pb chronology indicates that there were geotectonic-thermal events in 1,600-2,729 Ma in source area of Xiaomiao Formation,most ages of which are distributed in 1,683-1,554 Ma of the Middle Proterozoic in geological time.